Drying oven apparatus



FIG.2

April 5, 1960 J. sTRAuss 2,931,882 i DRYING OVEN APPARATUS oriinal Filed Feb. e, 1957 2 sheets-sheet 1 ATTOR N E YS April 5, 1960 J. sTRAUss 2,931,882

DRYING OVEN APPARATUS original Filed Fb. 6, 1957 2 sheets-sheet 2 lFIG.4 268 @@CDCDQQQ@ @@@QQQ @2G/200cm@ Fse 24| 273 275 INVENTOR.

Joseph Strauss ATTORNEYS Unit States Patent Hice Patented Apr. s, leso DRYING VEN APPARATUS Joseph Strauss, Hopewell, NJ., assigner to Trenton Times Corporation, Trenton, NJ., a corporation of Delaware Original application February 6, 1957, Serial No. 638,509. Divided and this application April 22, 1958, Serial No. 730,185

Claims. (Cl. 219-35) The present invention relates to a new and novel drying oven apparatus, and more particularly to a drying oven especially adapted for use in drying or burning-in operations in connection with printing plates and the like.

The present application is a division of U.S. patent application Serial No. 638,509, tiled February 6, 1957.

The present invention has general utility for performing drying operations, but. is particularly suited for drying printing plates formed, for example, of magnesium in carrying out drying or burningin operations on such plates as disclosed in my copending application Serial No. 638,509. When drying operations are performed on magnesium plates, distortion or buckling of the plates is a serious problem. Prior art ovens utilized for drying printing plates subject the plates to non-uniform heating producing undesirable results. In addition, prior art constructions allow foreign material and dust to settle into the interior of the oven. This is highly disadvantageous when magnesium plates having a cold-top enamel surface are dried in the oven apparatus since this type of a surface is especially prone to accumulate foreign matter.

The present invention employs a structure wherein the disadvantages of the prior art are overcome. The printing rplates are supported within the invention oven upon a support assembly including a main body portion of' mesh-like configuration kwhereby a small area of the surface of the printing plate is in contact with the body portion. In this manner the printing plate is uniformly heated, and the heat transferred from the plate to the supporting body is minimized. The invention oven apparatus is also constructed so as to have a rigid top and aplurality of hinged door members which enable the front portion of the oven to be opened. In this manner the supportassembly and the associated printing plate may be inserted horizontally through the front portion of the oven'. The printing plate will be protected at all times by the rigid top of the oven, thereby substantially eliminating the possibility of foreign material or dust accumulating on the soft cold-top enamel of a magnesium plate or the like.

An object of the present invention is the provision of a new and novel drying oven apparatus which is especially adapted for performing drying or burning-n operations` With magnesium plates having a soft cold-top enamel surface thereon.-

Another object of the present invention is the provision of a drying oven apparatus which provides substantially uniform heating to a printing plate or the like.

A further object of the present invention is to provide a drying oven wherein the accumulation of dust or foreign matter therein is minimized.

g A still further object of the present invention is to provide an oven apparatus which is simple and inexpensive, yet efcient and reliable in operation.

j Other objects and many attendant advantages of the present invention will become more apparent when contion and drawings wherein:

Fig. 1 is a perspective view of the drying oven with a portion of the top broken away and elevated to more clearly illustrate details of internal construction;

Fig. 2 is an enlarged sectional view of the support assembly mounting means;

Fig. 3 is a sectional view, taken on line 3-3 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is a plan view of the heating element system embodied in the burning-in oven top;

Fig. 5 is an enlarged sectional view illustrating details of the oven heating elements; and

Fig. 6 is an enlarged sectional view showing a portion of the supporting bed for the burning-in oven.

Referring now to the drawings wherein like reference characters designate corresponding parts throughout the several views, Fig. 1 illustrates the construction of a special drying oven utilized in practicing the novel method for preparing magnesium plates as disclosed in my copending U.S. patent application Serial No. 638,509. ln this figure, the drying oven will be seen to include a generally flat bottom wall 235 supported by a suitable number of legs 236 and having one or more drain openings 237 therein having drain pipes 238 issuing therefrom for a purpose which will be presently apparent. Projecting upwardly through the center of the bottom wallv 235 is a drive shaft 239 driven by a suitable gear box and motor assembly indicated generally by the reference character 240 located beneath the bottom wall 235. A support assembly 241 is mounted upon the upper end of drive shaft 239 in a novel manner. As seen most clearly in Fig. 2, a hub 205 is'secured to the lower portion of the support assembly and is provided with ,a bore 210 of non-circular cross section, shown as being square. bore 210 receiving the upper end of drive shaft 239 which is also of complementary square configuration and is received within bore 210. Hub 205 is also provided with a notch 213, the side walls 214 and 215 of which flare outwardly from the bore 210. The notch, as seen most clearly in Fig. 2, is not as deep as the bore 210 so that when the support assembly is engaged upon the upper end of drive shaft 239, the upper end of the shaft will be firmly seated within the square socket portion defined by the bore 210 above notch 213, and the support assem bly, due to its weight and the printing plate mounted thereon, will accordingly be locked upon the upper end of the drive shaft.

The purpose of notch 213 is to permit the support assembly to be easily engaged with the upper portion of the drive shaft since the divergent walls 214 and 21.5 serve as a guide for the upper end of the Vshaft as the support assembly is moved horizontally into engagement therewith until the parts are aligned so that the support assembly drops down as the blind socket portion in the hub aligns with and receives the upper end of the drive shaft 239.

The support assembly 241 includes a rigid bordering frame 242 which is connected at the four corners thereof to ribs 206, 207, 208, and 209 radiating outwardly from the hub as seen most clearly in Fig. 3. These ribs may be of conventional angle type, or any other suitable shape as desired. The rigid bordering frame 242 supports a main body portion formed of suitable mesh-like material 243 which preferably is constructed of stainless steel and is of the type which is conventionally referred to i as expanded metal.

support assembly 241 s illustrated. In this` ligure,

will be seen that the bordering frame Zil is preferably of angle conguration with the lower horizontal leg 244 thereof serving to edge support the expanded metal 243'. This leg portion 244 is provided with a series ofopenings to receive fasteners 245 which serveto clamp the edge portions of the expanded' metal between the previously mentioned leg 24d and' the loverlying strip 246 as shown. The expanded metal has the advantage of providing relatively widely spaced supporting points 247 which are relatively widely spaced and contactvery little surface area of the supported magnesium plate. By this construction, thereis less likelihood of distortion or buckling of the magnesium plate when the same is subjected to heat within the dryingl oven since the plate will be uniformly heated rather than being subjected to a non-uniform heating effect as would be occasioned where large surface arca portions of the plate contact with the metal of the support assembly 24d, causing a great deal or" heat to be transferred from the plate' to the support assembly in those portions in which the two are in contact. This excessive heat transfer is largely obviated by the use of the expanded metal construction since a very small percentage of the surface of the magnesium plate is actually in contact with the expanded metal body.

Referring back to Fig. l, the oven. apparatus is provided with a fixed back wall 248 which is opstanding from the bottom wall 235 and rigidly afxed thereto. Preferably, the back wall 245 extends throughout less than half the. total circumference of Ithe bottom wall 235 to permit free and ready access to the interior of the oven and to'permit the support assembly 241 and its boss to be easily engaged with the drive shaft 239.

The front portion of the side wall of the oven is constructed so as to form a plurality of hinged door members which will enable the entire front portion-of the` oven to Vbe opened to allow the support assembly Zdli, andthe associated plate 249"r to be placed in the interior of the oven. Preferably, each door is of the same length is divided into two portions hingedly connected together as is indicated by me reference characters 250 and 251 in Fig. l, the point of pivotal connect-ion between these sections bein-g indicated by Ithe hinges 252. The rear edge of the section 250 is hinged to the leading edge of the back wall portion 2-4-8 by means of hinges 253 and. the free edge of the front section 251; is provided witha suitable latch assembly 254 which cooperates with the latch assembly 255 on the section 256 of =the other door assembly so that the two may bev joined and held in closed position.

The oven also includes a rigid top member257 which is fixed to the upper edge 258 of the back wall 248, although in Fig. 1 a portion of the top has been shown broken away from the remainder andlifted up to illus-` trate details of the heatingelement construction'. It is to be understood that in actual practice the top will be at all times rigid with the back wallv 24Sy and in that position shown in the right hand portion ofFig. l.' reason for this. is that the drying oven is particularly useful in drying the resist image and by providing a fixed top and inserting the support assembly 241 and thefassociated plate 2e? horizontally through the. front of tbe assembly, the presence of dust is largely.y eliminated and there is little chance for foreign material and dust to.

accumulate on Ithe still sotcold-top enamel. Inconventional constructions of this type, the lid ortop. is hinged so as to swing up to permit the plate to placed. inside the oven and then the lid is sv ungdown to close the oven. rl`his type of conventional construction isprone to admit a great deal of foreign material irrttrth'eV interior of the oven and actually the act of closing the cover tends toV forcibly project foreign material onto the cold-top enamel surface.

The'top 2;*37 vis preferably' provided with a -rigidfying, cit-cumferential, depending .rib 25'?, the lower edge of which isxcd tov thc previously mentioned upper edge The- 258 of the back wall 248 and xed to the under-surface of the top 257 are a series of heating units such as that indicated by the reference character 250. For the purpose of heating the oven, it is preferred that the arrangement of heating units 26% lbe substantially as is shown in Fig. l wherein the elements 25?. designate heating bulbs or lamps.

The particular arrangement of the heating units 260 and the number of heating elements 2i: embodied therein is, of course, determined by the amount of heat required to properly dry the cold top on the plates, while at the same time maintain the temperature at such. a point as not to balie the enamel or dry it beyond the point which will permit it to readily take on the inl; top when the latter is applied. Gperating in conjunction with the particular number and arrangement of heating units, are certain control elements designated by the reference characters 262, 263 and 26dwhich are preferably, as shown, mounted on the 4top of the oven assembly so as to be readily accessible. These control elements include a starting or olf and on switch 262, a temperature control 263 and a rpm. control 254. The temperature control element 263 is connected with the heating units and controls the amount of energy applied thereto, whereas the r.p.m. control 264 is similarly connected to the motor and gear box assembly 24d for controlling the same. units is a thermostatic control mechanism including a bulb 265 mounted in a suitable manner on the undersurface of the top 257 and a control switch 266 preferablyl mounted on the upper face of the top 257. The purpose should a prescribed temperature be reached.

All of these control elements operate cumulatively to produce the desired results. That is, the rpm. in conjunction with the heat control operates to produce an even and uniform drying action on the plate 249 and the cold-top solution applied thereto. For this purpose, it is preferred that the rpm. control be set to rotate the plate initially at about 9G to 95 r.p.m. for 3() seconds with the heat control set at approximately F. The rpm. control is then adjusted to approximately 7() r.p.m. for l minute, then reduced to about 30 rpm. for 2 minutes and iinally'to about 6 to 8 rpm. for not less than l5 minutes. This procedure produces a uniformly and properly dried magnesium plate having a cold-top enamel surface.

Referring now more particularly to Fig. 4, a modified form of top assembly is shown which is to be utilized inv with that described in connection with Fig. l, is providedk with a far greater number of heating units 268 than the assembly shown and described in connection with Fig. l. The reason, of course, is that for the burning-in operations, a much greater amount of heat is required to produce the proper results, although the principle of operation remains the same. Each of the heating units 268 as well as those previously mentioned and indicated by the reference character 266 are formed'in a manner shown most clearly in Fig. 5 wherein the top 267 will be seen to be provided with slots 269 through which socket members 270 project for receiving the bulbs 271. Each of the heating units 26S includes a base portion 272 afxed to the undersurface of the top and a removable cover portion formed of the two side walls 273 and 274 and the associated bottom wall member 275 which is provided with circular openings 276 through which the lower portions of the individual bulbs 271 project. The sockets 270y are carried by the base portion 272 and the sockets themselves are provided with av covering member 277 which: ispreferred to be of the removable typeffor ease of servicing,-

Also operating in connection with the heating' When the oven apparatus yas disclosed in Fig. 4 is employed in a burning-in operation, the plate is first powdered in a conventional manner. In the method as disclosed in my aforementioned copending application, the burning-in oven is energized for 45 seconds while ythe temperature inside the oven is controlled by a thermostat at approximately 140 F. while the plate is rotated at a speed of approximately l r.p.m. This procedure will produce a very even burning-in and the etching powder will be fused properly and to the correct degree against the powdered side of the plate when using magnesium plates or the like.

It is apparent from the foregoing that there is provided a new and novel oven apparatus for drying or burning-in operations which is especially adapted for use with magnesium printing plates having a cold-top enamel surface. The apparatus provides a substantially uniform heating of plates utilized therewith, and minimizes the accumulation of dust or foreign material therein. The apparatus is simple and inexpensive in construction, yet cicient and reliable in operation.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

Iclaim: l r

1. A drying or burning-in oven for use in making printing plates, comprising a housing having vertically spaced bottom and top walls, vertical side walls rigidly fixing the top and bottom walls with respect to each other, a substantial portion of said side walls being hinged to the remaining portion thereof to form a swingable closure gaining access into the interior of said housing, a horizontal support disposed within said housing, means for rotatably mounting said support within said housing for rotation about a vertical axis therein, and a plurality of heating units mounted on the undersurface of said top wall, the means for rotatably mounting said support comprising a rotatable shaft projecting vertically upwardly into said housing and terminating in a squared upper end, said support having a hub fixed to its undersurface and provided with a square recess receiving the upper end of said shaft, said hub having a horizontalnotch therein opening upon the lower end of the hub and extending vertically therefrom to terminate short of the upper end of said hub recess, providing a horizontal entrance opening into said recess so that the support may be slid horizontally into engagement with said shaft while retaining a socket-like portion of the recess above the notch to fixedly receive the upper end of said shaft, the opposite sides of said notch being divergent outwardly from the' recess to guide said shaft into the recess.

2. A drying or burning-in oven for use in making printing plates comprising a housing having vertically spaced bottom and top walls, vertical side walls rigidly fixing the top and bottom walls with respect to each other, a substantial portion of said side walls being hinged to the remaining portion thereof to form a swingable closure providing access into the interior of said housing, a substantially horizontal support disposed within said housing, said support including a rigid border frame and a substantially open main body portion within and fixed to said border frame, said main body portion comprising expanded metal to provide relatively widely and equidistantly spaced coplanar portions of small area to support a printing plate resting thereon to obviate appreciable conductive transfer of heat from the plate and to provide a substantially uniform heat distribution within the plate, a substantially vertically extending drive shaft rotatably mounted within said oven, means connected to said drive shaft within said oven, means connected to said drive shaft for selectively driving the drive shaft at predetermined speeds of rotation, means removably securing said support to the upper portion of said drive shaft, and a plurality of heating units mounted on the undersurface of said top wall. f

3. An oven as defined in claim 2 wherein said side wall portion defining the access closure into said housing comprises greater than half the extent of said side wall.

4. An oven as dened in claim 2 wherein said closure portion of the side wall includes four separate elements, one of said elements being hingedly connected to each of the opposite edge portions of the remaining side wall portion, the other two separate elements each being hingedly connected to said one separate elements and being adapted to be positioned in abutting relationship to seal the interior of the oven, said closure portion comprising greater than half the extent of said side wall.

5. A drying or burning-in oven for use in making printing plates comprising a substantially cylindricalv housing having vertically spaced bottom and top walls, a vertical side wall rigidly connected between said top and bottom walls, a major portion of said side wall comprising a closure means, said closure means including a plurality of sections hingedly connected to one another whereby said closure section may be completely opened for gaining access into the interior of said` housing, a substantially horizontally disposed support means within said housing, said support means including a hub portion, a rigid border frame and a substantially open main body portion within and fixed to said border frame, said main body portion comprising expanded metal to provide relatively widely and equidistantly spaced coplanar portions of small area to support a printing plate resting thereon to obviate appreciable conductive transfer of heat from the plate and to provide a substantially uniform heat distribution within the plate, a substantially vertically extending drive shaft rotatably mounted Within said oven, means connected to said drive shaft for selectively driving the drive shaft at predetermined speeds of rotation, means removably securing said support means to the upper portion of said drive shaft, and heating means secured to the undersurface of said top wall for applying a substantially uniform heat to the interior of said oven.

References Cited in the tile of this patent UNITED STATES PATENTS 161,908 Smedley Apr. 13, 1875 1,054,321 Sinks Feb. 25, 1913 Y 1,477,844 Nystrom Dec. 18, 1923 1,534,072 Mursch Apr. 2l, 1925 1,737,293 Birch Nov. 26, 1929 1,785,079 Grapp Dec. 16, 1930 2,218,165 Gaebel Oct. l5, 1940 2,542,109 Benson Feb. 20, 1951 ,2,646,495 Dornbush July 2l, 1953 

